1. Field
The disclosure relates generally to vibratory bonding and more specifically to computer control of a bonding machine to perform its normal bonding function, and also to perform rework by allowing an operator to use the remotely controlled three axis motion of the bonding machine to position a sharpened wedge over a bridge between bonds and to cut the bridge.
2. Description of the Related Art
Ultrasonic Bonding is a known process for fusing electrical connections through the application of pressure and ultrasonic energy. Ultrasonic Bonding is performed by machines that are both computer-controlled and operator controlled. The Ultrasonic bonding machine has electrical motors for movement in the x axis, the y axis and in the z axis. Software allows a part to be indexed for precise movement in response to a joystick controlled by an operator. The operator moves an ultrasonic wedge into position while viewing the circuit through a microscope. The joystick enables the user to precisely place a bonding wedge onto the wire to be bonded. A weight attached to a wedge holder applies downward pressure to the wedge ensuring contact between the wedge and the wire to be bonded. When the operator is ready to initiate the bonding process, the operator presses a button on the joystick in order to send ultrasonic energy through the bonding wedge and onto the wire. The ultrasonic energy creates the bond.
When bonds are made in close proximity to other bonds, material from one bond may contact a neighboring bond. Such contact is referred to as bridging, and the bridge between the two bonds causes a short and results in a failure of the part at a continuity test. Shorts caused by bridging must be repaired, and the repair process is referred to as reworking the bond. The current method to rework the bond is for the operator to manually cut the bridge of material connecting two bonds using a sharp blade. The operator cannot precisely control the movement of the blade and the precision is only as good as the motor reflexes of the operator. Moreover, because the circuits to which the bonds are being applied are very small, the operator views the bridge and the bonds joined by the bridge under a microscope. Since the dimensions are so small, accurate manual movement of the cutting instrument is very difficult. Damage to components of the part can easily arise due to imprecision arising from the operators vision and motor reflexes. Furthermore, the manual operation of physically cutting the bridge between two bonds is difficult and time consuming.
What is needed beyond the prior art is a way to automate the rework process to eliminate manual manipulation of a cutting tool by the operator.